Mass functions for a simulation of 2000 sources with mass extracted from a Salpeter IMF (full black line). The full red line is a linear fit to the simulated mass function, where the slope is  −2.42    ±    0.02. The dash-dotted line is the mass distribution of the sources extracted form the simulated field. The red dash-dotted line is the linear fit to the distribution; the recovered mass function slope is 2.2  ±  0.1, and it agrees with the input one within a 2σ uncertainty.